An example of building management system according to the introductory paragraph is described in the brochure "IFS 800 Lighting control system" published by Philips Lighting. In this system each appliance, such as a luminaire, a heating or cooling device or a fan in a space, such as a room, office or shop area, is coupled with a central control system via a communication bus. In this particular system each appliance is controlled by a local controller unit which is connected to the communication bus and regulated by signals from the central control system. The local controllers comprise the necessary electronics for adjusting several appliances to required levels. An occupant of the space communicates a change of the desired levels to the control system by means of infra-red (IR) signals transmitted by a portable IR remote-control unit to an IR-receiver connected to the communication bus. Further, the known system allows additional determination of the desired levels by use of sensors, such as a presence detector, a thermometer or a light sensor.
Another known building management system, suitable for small complexes such as shops and restaurants, is the BatiBUS/ISIS system, commercialized by the company Merlin Gerin, Meylan, F-38240 France. In this system each appliance includes its own local controller which is connected to the communication bus. Security and alarms can be incorporated in this known system.
In the known systems the local controllers and the appliances are connected to the communication bus by wires. In a modem office building or commercial complex this is a drawback as spaces are often changed. Changing virtually always requires displacement of the appliances and often also tearing down and rebuilding of internal walls. To achieve a flexible floor lay-out at low cost, a minimum of wiring in the walls is required. However, it is also required by the users of a building to have full control over the location of the appliances, consequently placing appliances on predetermined spots only is unacceptable.